Compile-Time Warnings for Oracle DB 10g (Page 1 of 4 )
In this fourth part of a nine-part series on managing PL/SQL code, you will learn about the compile-time warnings that were introduced in Oracle Database 10g Release 1. This article is excerpted from chapter 20 of the book
Oracle PL/SQL Programming, Fourth Edition, written by Steven Feuerstein and Bill Pribyl (O'Reilly; ISBN: 0596009771). Copyright © 2006 O'Reilly Media, Inc. All rights reserved. Used with permission from the publisher. Available from booksellers or direct from O'Reilly Media.
Warnings Available in Oracle Database 10g
In the following sections, let’s take a look at most of the compile-time warnings that were introduced in Oracle Database 10g Release 1. I will offer an example of the type of code that will elicit the warning and also point out some interesting behavior (where present) in the way that Oracle has implemented compile-time warnings.
PLW-05000: mismatch in NOCOPY qualification between specification and body
The NOCOPY compiler hint tells Oracle that, if possible, you would like it to not make a copy of your IN OUT arguments. This can improve the performance of programs that pass large data structures, such as collections or CLOBs.
You need to include the NOCOPY hint in both the specification and the body of your program (relevant for packages and object types). If the hint is not present in both, Oracle will apply whatever is specified in the specification.
Here is an example of code that will generate this warning:
/* File on web: plw5000.sql */
CREATE OR REPLACE PACKAGE plw5000
IS
TYPE collection_t IS
TABLE OF VARCHAR2 (100);
PROCEDURE proc (
collection_in IN OUT NOCOPY
collection_t);
END plw5000;
/
CREATE OR REPLACE PACKAGE BODY plw5000
IS
PROCEDURE proc (
collection_in IN OUT
collection_t)
IS
BEGIN
DBMS_OUTPUT.PUT_LINE ('Hello!');
END proc;
END plw5000;
/
Compile-time warnings will display as follows:
SQL> SHOW ERRORS PACKAGE BODY plw5000
Errors for PACKAGE BODY PLW5000:
LINE/COL ERROR
-------- --------------------------------
3/20 PLW-05000: mismatch in NOCOPY
qualification between
specification and body
3/20 PLW-07203: parameter
'COLLECTION_IN' may benefit
from use of the NOCOPY
compiler hint
Next: PLW-05001: previous use of 'string' (at line string) conflicts with this use >>
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 This article is excerpted from chapter 20 of the book Oracle PL/SQL Programming, Fourth Edition, written by Steven Feuerstein and Bill Pribyl (O'Reilly; ISBN: 0596009771). Check it out today at your favorite bookstore. Buy this book now.
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